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A flywheel providing for the primary coolant pump running-down required by op-
erating conditions of the reactor unit in case of power failure is mounted on the electric
motor shaft. The flywheel is made of pearlitic steel forging, which has been thoroughly
mechanically tested, UT-tested and subjected to dye penetrant inspection. It is rated for the
operation in normal and transient conditions. The stress in the flywheel body does not ex-
ceed the stress permissible for this material. Flywheels of this type have proved to be effi-
cient in CVN-8 (centrifugal recessed impeller pump) pumps for RBM-K-1000 (pumps for
high-power channel-type reactors) at the same rpm. The torsion bar transferring rotational
movement to the pump shaft is fitted into a splined bush secured in the motor rotor bore.
All components and assembly units of the primary coolant pump, which are in con-
tact with the primary coolant, seal water and water from the intermediate cooling circuit,
are made of steel (or surfaced with steel) resistant to corrosion, intercrystalline corrosion
and erosion. The chemical composition of the materials used to make the components that
are in contact with primary coolant and seal water (including materials used in bearings
and mechanical shaft seal) are free of any specific additives forming long-lived isotopes.
Assembly units of the primary coolant pump has been thoroughly bench-tested and
proved to be efficient and reliable in the process of a long-term operation as the compo-
nents of the primary coolant pumps operated at NPP.
The bottom hydrostatic journal bearing is analogous to the bearing used in CVN-8
pump for RBM-K-1000 reactor unit. The said pumps are operated in the reactor units at
the Leningrad, Kursk and Smolensk NPP.
At the present moment, some of the said primary coolant pumps have been operated
for more than 80 000 h and no failures caused by faulty bearings have been reported so far.
The journal bearing, analogous in its design and friction couple materials to that,
used in the combined journal and thrust bearing of the primary coolant pump has been
thoroughly tested and already used in CVN-12 pump for RBM-KP.
The thrust bearing is analogous to the bearing developed for CVN-12 pump for
RBM-KP. It was tested during ~ 6000 h at unit load of ~ 5 MPa (the maximum unit load
reached ~ 7 MPa). No early wear of the working faces of the bearing were reported during
the test period.
The anti-reverse rotation mechanism is analogous to the mechanism used in CVN-8
pump for RBM-K-1000, which has proved to be reliable by long years of the operation in
the primary coolant pumps at different NPP.
Comparison of primary coolant pump designs.
In terms of performance operating con-
ditions, the pump discussed in this section is analogous to CVN-8 pumps for RBM-K-1000,
and GCN-195M and GCNA-1391 pumps for VVER-1000 reactor unit.
By now, field experience with these pumps have become extensive and has made it
possible to determine lines for improvement of primary coolant pumps for reactor units of
the next generation – NPP-92 (AES-92) and UVR-1500.
General arrangement of the pump which is now being developed is identical to the
ones discussed here – the pump unit consisting of a hydraulic housing a pull-out part and
an electric motor, and the pump and electric motor are coupled with a flexible link in the
form of a gear coupling with a torsion bar. The pull-out part consists of a shaft with two
journal bearings and a thrust bearing, and a mechanical shaft seal.
Major assembly units of the primary coolant pump have been selected based on
positive field experience with CVN-8 pump. However, unlike CVN-8 pump, in which just
one seal sage can actuate due to the lower pressure drop at the seal, the pump being devel-
